Evidence for Evolution

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Unit: Evolution

Topic: Evidence for Evolution
Class: Grade 10, Biology

Overview

The next three lessons help students understand how scientists find evidence of evolution and piece together the history of life. Students learn about the fossil record, the primary form of evidence. The lesson begins with an overview of the fossil formation process, then covers the evolution of land-dwelling animals from fish, and finally looks at how some mammals (whales) ended up back in the water. It then covers other evidence for evolution, including anatomy, embryology, and biochemistry. These lessons contribute or build toward the goals of the unit as a whole by almost taking a step back and now examining how we know evolution exists now that they understand what it is. They will be able to explore evidence and new definitions associated with evolution, more specifically, structural related definitions and ideas.

Links to Standards or Benchmarks


Link to Standards
"Unpacked" Standards

By the end of the 12th grade, students should know that
  • The theory of natural selection provides a scientific explanation for the history of life on earth as depicted in the fossil record and in the similarities evident within the diversity of existing organisms.
  • Life on earth is thought to have begun as simple, one-celled organisms about 4 billion years ago. During the first 2 billion years, only single-cell microorganisms existed, but once cells with nuclei developed about a billion years ago, increasingly complex multicellular organisms evolved.
  • Evolution builds on what already exists, so the more variety there is, the more there can be in the future. But evolution does not necessitate long-term progress in some set direction. Evolutionary changes appear to be like the growth of a bush: Some branches survive from the beginning with little or no change, many die out altogether, and others branch repeatedly, sometimes giving rise to more complex organisms.



Objectives

  • Define adaptations
  • List and describe evidence for evolution (Fossils, Anatomy, Embryology, Biochemistry)
  • Explain how and why structural adaptations arise over time
  • Describe how scientists use fossil evidence to trace the evolution of various species
  • List and describe methods used to date fossils

Suggested Time

  • Three class periods (90 minutes each)

The Lesson:

Day 1: Fossil Formation


  1. 5 minutes: Have the students answer the question of the day in their journal: Did you ever wonder what was here on Earth before you were born. What plants? Which animals? To uncover our past we have to dig down into the Earth and look for fossils. What are fossils? How are they formed?
  2. 5 minutes: I will then ask the class to share some of their ideas. I will write their ideas on the board, whether correct or incorrect. Next I will tell them: Today we will find out which of these ideas are correct! I will then go over the agenda for the day and explain that today's lesson is important because it will provide them with evidence for evolution which not only is good for the skeptic, but helps one to better understand evolution.
  3. 10 minutes: I will have the class watch the Becoming a Fossil video and read the backgrounder.
  4. 15 minutes: Lecture and discuss the following questions, writing notes on the board:
    • Why do most living things not leave fossils behind?
    • How are fossils formed?
    • How are fossils found?
    • How do scientists determine the age of fossils?
  5. 10 minutes: Have the students watch the Radiometric Dating video and take notes. Then discuss in class the process of radiometric dating.
  6. 30 minutes: Split the students into 4 heterogeneous groups and have them complete a jigsaw activity. I will assign each group one of the following topics: fossil formation, relative dating methods, radiometric dating, and other chronometric techniques. Each group will collect information on their assigned topic from a handout I will give them titled Record of Time . Each group will read their about their assigned topic and pick out 10 important pieces of information as a group (15 minutes). Next, I will again split the students up into group of 4, all including 1 student from each original group. The students will report the information their group had agreed on and teach it to their new group (15 minutes)
  7. 10 minutes: I will discuss the results as a class.
  8. 5 minutes: I will hand out and explain their homework, which is to have the class read the interview Mike Novacek: Fossils in the Gobi. This interview will give them a good sense of what it's like to be a paleontologist. It shows how an individual scientist contributes to the fossil record and our understanding of evolution. They will then answer the following questions on a separate piece of paper.
  • Who is Roy Chapman Andrews?
  • Why were Andrews's mammal fossil finds important?
  • What did Novacek learn about mammals from the dinosaur age? What evidence did he find to draw these conclusions?
  • What did Novacek learn about the transitions in mammalian evolution?


Day 2: Fish with Fingers


  1. 5 minutes: Have the students answer the question of the day in their journal: There is a common belief that fish-like creatures evolved limbs for life on land after being stranded on land. Do you believe that this is true? Why or why not? How could fish-like creatures, stranded on land, somehow evolve limbs and survive to become the first tetrapods?
  2. 5 minutes: I will then ask the class to share some of their ideas. I will write their ideas on the board, whether correct or incorrect. Next I will tell them: Today we will find out which of these ideas are correct! I will then go over the agenda for the day and explain that today's lesson is important because they will further look at evidence, but this time at unusual findings, which could help to explain why members of a species are all so similar.
  3. 15 minutes: Have students watch the Fish with Fingers video and read the backgrounder.
  4. 10 minutes: Discuss the following questions in class: Why was Jenny Clack unsatisfied with the explanation of how land-dwelling animals evolved? What evidence did she find to disprove old theories? What explanation can Clack give based on her fossil evidence?
  5. 20 minutes: Lecture on how structural adaptations arise over time and other evidence for evolution, writing notes on the board. (part 1)
  6. 20 minutes: Have the students read the interview with Ted Daeschler and Neil Shubin called Ted Daeschler and Neil Shubin: Early Tetrapod Fossils. Then have them draw a line down the center of a sheet of paper. In the left column have them list examples of types of fossil structures the scientists found. In the right column have them explain what the scientists learned from this evidence.
  7. 10 minutes: Discuss results and write notes/draw representation on board.
  8. 5 minutes: Explain homework, closing comments and questions. Homework is to answer the following questions:
    • What are some key examples of fossil evidence that support the theory of evolution?
    • Why are fossils so rare, and why is it difficult to find an evolutionary trail of fossil species leading from a common ancestor?
    • What questions remain unanswered by relying solely on the fossil record?



Day 3: Whale Evolution & Other Evidence for Evolution


  1. 5 minutes: Have the students answer the question of the day in their journal: Yesterday we learned what types of evidence are used to learn about evolution. What are they? (fossil, molecular, chemical, anatomical).
  2. 5 minutes: I will then go over the agenda for the day and explain that today's lesson is important because it will give them an opportunity to explore how some completely unrelated species have similarities and why and how this is so. I will then discuss the question and write the list on the board and discuss what each term means.
  3. 10 minutes: Show the Evolving Ideas: How Do We Know Evolution Happens? video.
  4. 15 minutes: Verbally discuss the following questions with the class and write notes on the board: What can we learn from fossil evidence? How do the transitional fossils of whales support the theory of evolution by natural selection?What specific fossil evidence points to whales' evolution from land to water?
  5. 20 minutes: Lecture on how structural adaptations arise over time and other evidence for evolution, writing notes on the board.(part 2)
  6. 10 minutes: Show pictures and discuss Embryo Comparison explaining that the presence of such similar genes doing similar things across such a wide range of organisms is best explained by their having been present in a very early common ancestor of all of these groups.
  7. 10 minutes: Show pictures and discuss Structural Homologies(Structural Homologies 1, Structural Homologies 2) explaining that a structure is similar among related organisms because those organisms have all descended from a common ancestor that had an equivalent trait.
  8. 5 minutes: Wrap up, closing comments and questions.

Materials Needed

*
Multimedia Resources

  • Computer
  • Overhead Projector

Multimedia Resources


Assessing Student Understanding


  • I will be able to assess the student's understanding by classroom questions/discussion, observation, through reading their journals, and through their graded homework assignment.

Cautions

  • There are no dangerous or hazardous components of the activities associated with the lesson.

Sources

Rationale

  • I included many different methods to teach, using lectures, readings, video, and pictures. Not only will this tap into multiple intelligences, but it will also break up the long 90 minute period!